This project is designed to investigate how chemical modification of hemoglobin with derivatives of vitamin B6 can affect the equilibrium of hemoglobin with oxygen in the presence of carbon monoxide. Particular attention will be directed to the allosteric effect by which partial saturation with carbon monoxide influences oxygen unloading. Whenever possible these studies will be extended to hemoglobin variants with high and low oxygen affinity. The penetration of red cells by the pyridoxal derivatives used for the chemical modification of hemoglobin will also be investiated.